pukunui
Legend
Looks like it's just in his head. I don't see anything along those lines in the cosmology chapter. (It's not in the Lore Glossary entry on the First World either.)Interesting tidbit here, and Wyatt isn't sure if he put thisnin the book or juat the idea in his head: the Shadowfell and Feywild are noy echoes of Material Prine worlds like the Forgettern Realma or Hreyhawk, but wxhoses of the shattered First World. So both Shadowfell and Feywild can cross between different Settings, because they reflect the unbroken world thst prexists the current D&D Multiverse.
It's a cool idea, though. One that I might adopt myself.